Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F10/00—Homopolymers and copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond

Definitions

• ABSTRACT A catalyst for polymerisation of ethylene and other alpha-olefins comprising a combination of a metallorganic derivative of the elements belonging to groups 1A, 11B and "IE of the periodic system and a supported halide of a transition metal of group W8 and VB of the periodic system, the said supported halide being obtained by reaction of the halide with the solid product resulting from suitable deposition of metallic aluminium on an activated alumina and/0r silica and- /or silico-aluminate.
• the present invention relates to a process for the polymerisation of olefins and in particular to a process for the preparation of polymers from ethylene and alpha olefins and of copolymers of ethylene with alpha olefins.
• the invention relates to catalysts suitable for the preparation of polymers from ethylenes and alpha olefins and copolymers of ethylenes with alpha olefins, and a process for the preparation of such catalysts.
• Yet another aspect of the invention relates to catalysts suitable not only for polymerisation of oefins but also the stereospecific polymerisation of alpha olefins.
• the polymers and copolymers of olefins can be obtained by polymerising the monomers with catalysts of the Ziegler type, such catalysts being the products obtained by bringing into contact compounds of transition metals with metals, hydrides or organo-metallic derivatives of the elements belonging to groups IA, IIB and [118 of the periodic system.
• titanium trichloride may be produced by reduction of titanium tetrachloride under suitable conditions by different reagents such as hydrogen, metallic aluminium or an organic derivative of aluminium, or by photochemical decomposition at ambient temperature of titanium trichloromonoalkyl groups obtained by reaction of titanium tetrachloride and aluminium alkyls at low temperatures.
• Titanium tri-chloride may also be produced from titanium tetrachloride directly in the reaction medium or immediately prior to polymerisation. This process, too, has drawbacks, particularly considerable operative difficulties due to the series of delicate and complicated operations which have to be performed industrially.
• the catalytic activity of stereospecific catalysts based on titanium trichloride, however produced, is not particularly high, so that the polyolefins obtained have finally to be subjected to very thorough purification processes in order to eliminate the residues of catalyst and this has the effect of substantially burdening the costs of the final product.
• catalysts have been proposed for the stereospecific polymerisation of alpha-olefins, wherein the titanium trichloride is deposited on the inert solid supports which are of large active surface area.
• the supported catalysts are frequently used in industry by virtue of the many advantages which lie in their use, particularly the high activity due to the great active surface area and the substantial simplifications in the processes of purification of the end products.
• titanium trichloride may not be deposited as such on the solid inert supports of large surface area without substantial losses of activity and stereospecificity.
• the said catalysts can be applied to the stereospecific polymerisation of propylene, in the polymerisation of ethylene and in the polymerisation of ethylene with propylene and l-butene.
• the said catalysts are characterised in that their behaviour is well-defined and constant, since the conditions in which they are prepared are easily reproducible and therefore produce polymers of clearlydefined and constant properties.
• ethylene and/or the alpha olefins are polymerised in the presence of a solid catalyst comprising a combination of a metallorganic derivative of the elements belonging to groups IA. 11B, and [MB of the periodic system and a supported halide of a transition metal of group [VB and VB of the periodic system.
• the said supported halide being obtained by reaction of the halide with the solid product resulting from suitable deposition of metallic aluminium on an activated alumina and/or silica and/or silicoaluminate.
• aluminas and silico-aluminates in the preparation of catalysts for the polymerisation of ethylene and/or alpha olefins.
• the aluminas and the silicoaluminates used for such purposes have to have particular structures and well-defined characteristics of surface area, porosity and reactivity with respect to the halides of the transition metals.
• the catalysts of the present invention can however be obtained from any type of alumina and/or silica and- /or silico-aluminates independently of the chemicophysical characteristics, although of a surface area at least greater than 10 sq.m/g and a granulometric distribution comprised in the range from 10 to microns.
• aluminas, silicas and silico-aluminates both the commercial grades and those obtained by calcination of hydroxides of precipitation, according to the invention, must 'be subjected to an activation treatment.
• the said treatment consists in subjecting the aluminas, silicas and silico-aluminates, for example in rotary kilns or in a fluid bed reactor, to a temperature ranging from 350 to 900C, for a period ranging from 2 to 25 hours, and preferably at a temperature ranging from 450 to 650 for a time ranging from 5 to 15 hours, in an atmosphere of anhydrous air or nitrogen.
• One of the essential aspects of the present invention is the phase involving deposition of metallic aluminium on the aluminas, silicas and/or silico-aluminates activated as above.
• the deposition phase may be carried out by various methods.
• a mixture of a metallic aluminium powder and an alumina and/or silica and/or sil ico aluminate is maintained at a temperature above the melting'point of aluminium for a period ranging from- 5 to 20 hours.
• This mixing of powders may be carried out either mechanically or by suspension of the aluminium powders and particles of alumina and/or silica and/or silicoaluminate in an hydrocarbon solvent, for example npentane or n-heptane, the solvent being subsequently evaporated.
• an hydrocarbon solvent for example npentane or n-heptane
• the granulometry of the aluminium powder becomprised in the range from 0.1 to microns.
• the working temperature ranges from 700 to 1000C
• the working time ranges from 10 to hours, with mixtures containing aluminium powders of a granulometry ranging from 0.5 to 5 microns.
• the quantity of aluminium is so regulated that the end product has a highly dispersed aluminium content of between 0.05 and 5% by weight.
• the metallic aluminium may also be deposited by initially impregnating the activated aluminas and/or silicas and/or silicoaluminates, with aluminium hydride or a metallorganic product of aluminium, both in solution.
• As solvents for the hydrides it is possible to use alphatic or aromatic ethers, for example ethyl ether, while for the metalloorganic compound it is possible to use aliphatic or aromatic hydrocarbons, for example heptane or benzene.
• lmpregnation is preferably performed in a fluid bed at a temperature ranging from to 100C, and even more preferably 20 to 40C, the solvent being eliminated by evaporation at the actual impregnation temperature over a period of 1 to 10 hours and preferably 1 to 5 hours.
• the impregnation phase is then followed by an activation phase at a temperature above that of decomposition of the hydride or of the metallorganic aluminium compound.
• the working temperature is at least 30C higher than the decomposition temperature of the hydride or of the metallorganic compound, the working time ranging from 5 to 20 hours, and preferably 10 to 15 hours.
• the quantities of hydride or aluminium metallorganic compound are so regulated that the solid end product in this case, too, have a content of highly dispersed aluminium ranging from 0.05 to 5 percent by weight.
• the product which is obtained in this way is then caused to react with a halide of a transition metal of groups lVB and VB of the periodic system, and more particularly with the chlorinated derivatives of titanium or vanadium, preferably titanium tetrachloride or vanadium oxychloride.
• the reaction is carried out at a temperature between and 350C and preferably between 225 and 300C, in apressure resistant reactor if the presence of a liquid phase is desired, or in a fluid bed reactor.
• the relative quantities of reaction of chlorinated derivatives of titanium or vanadium and the solid support are so regulated that the molar ratio of chlorinated derivatives to supported metallic aluminium ranges from 100 to 1000 and preferably from to 400.
• the reduction of the halide of the transition metal is substantially completed in from 10 to 30 hrs.
• Any residues of titanium tetrachloride are carried away by a suitable washing process, for example with n-heptane.
• the resultant solid catalyst consisting of the halide of the transition metal, in reduced form, finely dispersed on the support, is activated by means of an organometallic compound chosen fromamong the organic derivatives of metals of groups IA, 118 and IE of the periodic system.
• organometallic halides and completely alkylic derivatives particularly aluminium trialkyls, the halides of dialkyl aluminium and zinc dialkyls. These latter also act as molecular weight regulators.
• the relative quantities of organometallic compound and fixed transition metal are so regulated that their molar ratios are comprised between 5 and 100, preferably between 10 and 50.
• the catalyst may be activated immediately prior to introduction of the monomers, directly in the polymerisation reactor in intermittent tests or in a suitable reactor upstream of the reaction system if the process is continuous.
• the temperature at which such activation occurs is between 20 and 100C and preferably between 40 and
• the activated catalyst may also be left to mature for a more or less prolonged period at the activation temperatures.
• the catalytic system which is thus obtained is used for the polymerisation and copolymerisation of olefins and in particular for the preparation of polyethylenes, polypropylenes and copolymers of ethylene/propylene and ethylene/ l -butene, in which the ethylene is present in quantities equal to or greater than 90 percent or less than 10 percent by weight.
• Polymerisation and copolymerisation may be carried out by the known techniques: in the gaseous phase or in a liquid heterogeneous phase.
• reaction is carried out in the presence of an aliphatic or aromatic inert hydrocarbon diluent at temperatures comprised between 50 to 100C and at pressures of between 5 and 35 atm.
• Solvents which may be used are for example saturated aliphatic hydrocarbons, aromatic hydrocarbons and chlorinated hydrocarbons, for example chlorobenzene, heptane, pentane, benzene, cyclohexane.
• Polymerisation may be carried out in a steel pressurised autoclave into which are introduced the anhydrous solvent, in which the catalyst is suspended in quantities of 50 to 500 mg/l, and also the monomers in gas or liquid form.
• the polymers are obtained in the form of powders of controlled granulometry, which is a function of the granulometric distribution of the initial catalyst, with yields comprised between 80 and 120 kg/g of transition metal.
• Working according to the present invention has the further advantage that during polymerisation, small quantities of waxes form so that in a continuous process, by filtering out any cloudiness emanating from the reactor, in an anhydrous and inert ambient, it is possible to recover a substantial portion of organometallic compound and to recycle it to the reaction medium.
• the solid polymer obtained after filtration is treated with steam so, as to decompose the catalyst, eliminate the traces of residual solvent and carry out a purification, although on a minimal scale.
• the medium is then cooled to 40C, the air being replaced by dry nitrogen, and, still under conditions of fluidity and in a stream of nitrogen, the alumina is impregnated with a solution of ethyl ether containing 1 percent aluminium hydride until the aluminium hydride content of the alumina is equal to 0.52 percent by weight.
• the ethyl ether is then eliminated over a period of 5 hours at 40C.
• the temperature of the mixture is raised to 250C the whole being maintained at that temperature for 12 hours, fluidised conditions still being maintained, together with a stream of nitrogen.
• the solid product obtained was subjected to repeated washings in a suspension of anhydrous heptane in order to eliminate the final traces of titanium tetrachloride.
• the product obtained after filtration and drying consisted substantially completely of supported titanium trichloride with a titanium titre equal to 0.73 percent.
• EXAMPLE 3 50 g of commercial alumina of the same type as that described in Example 1 were added to 1 g of an aluminium powder of high purity with a granulometric distribution of 0.5 to 5 microns and the whole was closely blended. The resultant mixture was placed in a small rotary oven in which a weak flow of nitrogen was maintained. The temperature was raised to 750C and the whole was kept at that temperature for 15 hours.
• Example 1 It was then cooled, still in a stream of nitrogen, after which a greyish powder was obtained. 20 g of that powder were then transferred, together with 50 ml of titanium tetrachloride (specific gravity 1.72 g/cc) into a cylindrical pressure-resistant stainless steel reactor rotating about its axis, after the same procedure was adopted as in Example 1.
• the end product consisted virtually completely of supported titanium trichloride with a titanium content equal to 0.8 percent.
• EXAMPLE 4 500 ml anhydrous heptane containing 135 mg of a catalyst prepared as in Example 3 and 500 ml anhydrous heptane containing 770 mg diethyl aluminium chloride were placed in an autoclave such as that described in the previous examples. 120 g of propylene were then added to the autoclave and then, working at 80C, the pressure was raised to 12 kg/sq.cm by the introduction of ethylene. These conditions were maintained for 3 hours, ethylene being continuously supplied. ln this way, 93 g of ethylene-propylene copolymer were obtained, with the following properties:
• the relative quantities of transition metal halide and solid support used in the reaction being so regulated that the molar ratio of transition metal halide to supported metallic aluminum is between 100 and 1000, and in that,at a temperature of 20 to 100C the prodnot of such reaction is brought into contact with an organometallic compound chosen from aluminum trialkyls, halides of dialkyl aluminum, or zinc dialkyls, the relative quantities of organometallic compounds and of fixed transition metal being so regulated that their molar ratios are comprised between 5 to 100.
• Process according to claim 2 characterised in that the mixtures are prepared from a metallic aluminium powder of a granulometry between 0.5 and 5 microns and in that such mixtures are maintained at a temperature between 700 and 1000C for a period of between 10 and 15 hours.
• Process according to claim 2 characterized in that the mixtures of aluminum powder and particles of alumina, silica, silico-aluminate or mixtures thereof are prepared by suspension of the powders of aluminum and particles of alumina, silica, silico-aluminate or mixtures thereof in a hydrocarbon solvent, after .which the solvent is evaporated.
• solvents for the hydrides are aliphatic or aromatic ethers while solvents for the metallorganic compounds are aliphatic or aromatic hydrocarbons.
• transition metal halide used is titanium tetrachloride or vanadium oxychloride.
• Process according to claim 1 characterized in that said compound chosen from aluminum trialkyls, halides of dialkyl aluminum or zinc dialkyls is used in quantities such that the molar ratios, with respect to the fixed transition metals, are comprised between 10 to 50, the temperature at which these ingredients are brought into contact being regulated in the range from 40 to 100C.

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• Chemical Kinetics & Catalysis (AREA)
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• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Transition And Organic Metals Composition Catalysts For Addition Polymerization (AREA)

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• 1971
  • 1971-12-27 IT IT32949/71A patent/IT951956B/it active
• 1972
  • 1972-12-15 GB GB5811472A patent/GB1403208A/en not_active Expired
  • 1972-12-19 CH CH1843772A patent/CH583752A5/xx not_active IP Right Cessation
  • 1972-12-21 CA CA159,721A patent/CA988070A/en not_active Expired
  • 1972-12-22 DE DE2263124A patent/DE2263124C2/de not_active Expired
  • 1972-12-22 FR FR7246049A patent/FR2165997B1/fr not_active Expired
  • 1972-12-26 JP JP734203A patent/JPS5033975B2/ja not_active Expired
  • 1972-12-27 US US318812A patent/US3897364A/en not_active Expired - Lifetime
  • 1972-12-27 YU YU3248/72A patent/YU35512B/xx unknown
  • 1972-12-27 NL NL7217659A patent/NL167974C/xx not_active IP Right Cessation

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